Three dimensional bag with reinforced bottom and method of forming same

ABSTRACT

A SIDE SEALED, GUSSETED BOTTOM PLASTIC BAG AND THE METHOD OF FORMING THE SAME WHEREIN THE BOTTOM FORMING SEAMS ARE REINFORCED BY PROVIDING DIAGONAL FLAT SEALS INWARDLY FROM THE JUNCTION AREA OF THE GUSSET INNER FOLD LINE AND THE SIDE SEAL LINES, TO THE GUSSET OUTER FOLD LINES WITH THE SIDE SEALS CONNECTING THE ENDS OF THE GUSSET WALLS TO THE SIDE WALLS BEING CONTINUED TO THE OUTER GUSSET FOLDS, SO AS TO RELIVE THE STRESS AT THE JUNCTION POINT WHEN THE BAG IS FILLED AND THE BOTTOM OPENED OUT INTO SQUARE OR RECTANGULAR FORM.

NOV. 9, 1971 PlAZZE 3,618,478

THREE DIMENSIONAL BAG WITH REINFORCED BOTTOM AND METHOD OF FORMING SAMEFiled July 51, 1969 Ml .H" a

INVENTOR THOMAS E. PIAZZE MM WZMPQJQ) ATT 'YS.

Patented Nov. 9, 1971 3,618,478 THREE DIMENSIONAL BAG WITH REINFORCEDBOTTOM AND METHOD OF FORMING SAME Thomas E. Piazze, Mount Vernon, Ohio,assignor to Continental Can Company, Inc., New York, N.Y. Filed July 31,1969, Ser. No. 846,536 Int. Cl. B31b 49/04; B65d 31/10, 33/00 US. Cl.93-35 SB 7 Claims ABSTRACT OF THE DISCLOSURE A side sealed, gussetedbottom plastic bag and the method of forming the same wherein the bottomforming seams are reinforced by providing diagonal flat seals inwardlyfrom the junction area of the gusset inner fold line and the side seallines, to the gusset outer fold lines with the side seals connecting theends of the gusset walls to the side walls being continued to the outergusset folds, so as to relieve the stress at the junction point when thebag is filled and the bottom opened out into square or rectangular form.

The present invention relates to flexible bags and methods offabricating the same from heat sealable plastic film so as to provide,when opened up, a square or rectangular bottom structure.

Bags for packaging various products have been provided heretofore whichare fabricated from a web of relatively flexible plastic sheet materialwhich is initially folded with a gusset at the fold line andtransversely severed and sealed at intervals so as to provide a sideseal tubular bag structure with a square or rectangular bottom whenopened up which is capable of assuming an upright position when filledwith a product. One such bag structure which has been found satisfactoryfor packaging numerous products is described in my Pat. No. 3,023,679,dated Mar. 6, 1962. Experience with this bag, when fabricated fromthermoplastic films of various types and gauge, has indicated thedesirability of providing some reinforcement in the bottom seam areas,particularly, when the bag is designed to be used in the packaging offlowable materials having substantial weight such as, for example, sugarand like granular materials. It is a general object, therefore, of thisinvention to provide a side sealed bag of this type in which the bottomis reinforced so as to relieve the stress in the bottom seam areas.

A more specific object of the invention is to provide a side sealed bagand a method of fabricating the same from heat scalable plastic filmmaterial wherein special supplementary seals are provided in thegusseted bottom structure which strengthen the bottom end areas andreduce the likelihood of the seals rupturing when thebag is filled witha flowable product of substantial weight.

A further object of the invention is to provide a side sealed gussetedbottom plastic bag structure wherein the ends of the gusset bottom foldsare sealed to the side walls by extensions of the side seals and also bysupplemental fiat seals extending inwardly from the junction of thegusset inner fold line and the side seal lines to the outer gussetfolds.

A still further object of the invention is to provide a side sealed,gusseted bottom, plastic bag structure in which the side seals areextended to the outer gusset folds and supplemental reinforcing bottomseals are provided which extend from the intersecting points of theinner gusset fold and the side seal lines diagonally inwardly'to theouter gusset folds at a 45 angle so that the resulting triangular webslie fiat against the bottom portions of the side wall when the bag isset up and filled so as to reinforce the same.

These and other objects and advantages of the invention will be apparentfrom a consideration of the bag structure and the method of fabricatingthe same which are illustrated in the accompanying drawings wherein:

FIG. 1 is a diagrammatic top plan view, partly broken away, illustratinga method and apparatus employed in fabricating a bag structure whichembodies the invention;

FIG. 2 is a diagrammatic side elevation, partly in section, illustratingthe method and apparatus shown in FIG. 1;

FIG. 3 is a perspective view, with portions broken away, of the bottomportion of one of the flattened bag forming units;

FIG. 4 is a perspective view of the bottom portion of one of the bagunits in fully opened condition;

FIG. 5 is a fragmentary cross section taken on the line 5-5 of FIG. 4,to an enlarged scale; and

FIG. 6 is a cross section, taken on the line 6 6 of FIG. 4, to anenlarged scale.

The bag and the method of fabricating the same will be best understoodby reference first to the details of the bag structure which it isdesired to fabricate. Referring then to FIGS. 3 to 6, the bag 10, whichis illustrated, comprises two generally rectangular wall forming panels11 and 12 which, in collapsed condition, as shown in FIG. 3, areflattened upon each other and connected along the side edges bybead-like seals or welds 13 and 14. Generally, the panels 11 and 12 aremade of different lengths so as to provide a lip (not shown) at thefilling end of the bag. The bag bottom is formed, when the bag isfabricated, in a folded edge connecting the two wall panels 11 and 12,the fold being a bellows-type or being an infolded gusset so as toprovide a bottom structure consisting of panels 16 and 17 on oppositesides of a center fold line 18, which panels 16 and 17 are adapted, whenthe bag is set up, to open into coplanar, bottom forming relation withtriangular sections or extensions 20 and 21 at opposite ends. Thetriangular sections 20 and 21, which unfold into the plane of thevertical end or side walls 22 and 23, terminate at converging flat heatseals 24, 24 and 25, 25'. The flat heat seals extend at each end fromthe corners of the bottom wall formed by the panels 16 and 17 inwardlyat a 45 angle to a meeting point with the side seals 13 and 14,indicated at 26 and 27. The meeting points 26 and 27 are at the junctureof the gusset inner fold 18 and the side seals 13 and 14 and are spacedfrom the bottom ends of the side seals 13 and 14, the latter beingextended in the flattened condition of the bag to the bottom fold lines28 and 30 of the infolded gusset and connecting the ends of the gussetfolds to the adjacent side wall portions, the bottom extensions thereofbeing indicated at 13' and 14'. This results in triangular areas at thebase of the vertical side or end walls 22 and 23, in the set upcondition of the bag, in which there is a multiple thickness ofmaterial, these areas being defined by the flat seal lines 24, 24' and25, 25' and the respective bottom edges of the bag. The innermost wallsections are the triangular sections 20 and 21 formed in the gussetmaterial over which lie outer webs of triangular shape and substantiallythe same dimensions but having two thicknesses of film material whichare joined along the edge seal extensions 13 and 14' and which extend tothe flat seals 24, 24' and 25, 25' with the material being derived fromthe end portions of the infolded gusset. While this triangular doubleply section is not sealed on its face to the associated confrontinginner wall section 20, 21, it overlies the same when the bag is openedup and filled and hugs the surface thereof so as to reinforce the sealareas by relieving stress therein. It further serves to square up thebottom since the lowermost edge has a width corresponding to thecombined width of the bottom forming panels 16, 17 and defines thebottom edge of the side walls 22 or 23 so that a more nearly square orrectangular shape is imparted to the bag bottom and the product isrestrained against distorting the same.

Referring to FIGS. 1 and 2, there is illustrated a method of fabricatingthe bag in which a web 30 of stock material is employed which isselected according to the requirements of the material to be packaged.For example, a polyethylene film having good heat sealingcharacteristics and of a suitable weight or gauge depending upon the useto which the bag is to be put. The stock material 30 is fed from asupply roll (not shown) and folded on a longitudinal fold line intooverlapping relation with top and bottom folds 31 and 32 being offset atthe free edge to form a lip on the bag sections, the latter beingsubsequently determined by dividing and sealing or welding the plies ofthe folded material on transverse lines spaced at intervals along thelength thereof. The folded web is advanced to a gusseting station 33where a conventional gusseting wheel 34 and associated mechanism infoldsthe material at the folded edge so as to form a gusset therein of awidth which corresponds to twice the width of the bottom panel of thebags which are subsequently formed from the material. Prior to thefolding and gusseting operations, a means for preventing heat sealing isapplied to the pleat outer surfaces which are not to be joined by thesealing bars. Preferably, the web is printed with a pattern of the sealpreventing material as disclosed in my Pat. No. 3,023,679. The foldedand gusseted web advances through a pair of gusset back rollers 35 to aseal forming apparatus indicated at 40 which applies fiat heat seals,lndicated at 41, top and bottom of the gusseted area. The heat sealingapparatus 40 comprises a top sealer 42 and a bottom sealer 43 which arereciprocably mounted so as to engage on the top and bottom faces of thegusset fold portion of the web as it is advanced. The top and bottomsealers 42 and 43 each have a triangularshaped flat seal forming heatedbar as indicated at 44 in FIG. 1. The two legs of each of the sealingbars 44 are at right angles and the sealing devices 42 and 43 areoperated to form the seals, indicated at 41 in FIG. 1, in the gussetplies and the adjoining side wall portions, with the innermost plies ofthe gusset material remaining unsealed. The fiat seals 41 are applied atintervals spaced longitudinally of the film so that separation of theweb by a hot knife 45 on a transverse line, indicated at 46, in FIG. 1which extends through the apex of the triangle results in side seals 13and 14 on the trailing edge of the leading bag forming section and onthe leading edge of the next adjacent bag forming section with the seals41 being divided and forming the seals 24, 24 and 25, 25 in adjoiningbag sections and with each of the latter being at 45 relative to thetransverse sealing lines 46 and the outer gusset folds. The web isadvanced through a pair of draw rollers 47 to the hot knife 45 which hasa cooperating anvil roller 48 and which simultaneously severs and sealsthe material on a transverse line in which the apex of the triangularseal 41 lies. Suitable controls (not shown) for advancing the web areprovided to insure proper registration of the severing and sealing knife45 and the triangular seals 41. The knife 45 extends the full width ofthe web material and upon operation the leading end portion of the webbecomes a completed bag which is advanced between a pair of dischargeconveyor belts or the like (not shown) to a stack or other accumulatingarea. The apparatus is designed for continuous operation in high volumeproduction. The speed with which the bags can be produced depends uponthe speed and efiiciency of the bottom seal forming mechanism 40 andthis can be designed to achieve relatively fast and eflicient operation.

I claim:

1. A bag formed from a sheet of heat sealable plastic film materialwhich is folded upon itself in making the bag with a bottom wall forminggusset at the fold line and having side wall forming panels connected byside edge seals, said side edge seals extending from the outer gussetfolds to the opposite edge of the folded sheet, and bottom reinforcingseals extending diagonally inward from the points where the gusset innerfold line intersects the side edge seals to the gusset outer fold linesand joining the ends of the panels formed by the gusset folds to theportions of the side walls which extend beyond the intersection of saidgusset inner fold line and said side edge seals, whereby, when the bagbottom is opened up, a rectangular bottom is formed and triangularportions at the bottom of oppositely disposed side wall panel sectionsoverlie triangular portions at the ends of the bottom wall which lattertriangular portions open up into the plane of said side wall sectionsand co-operate therewith in forming a reinforced triangular area at thebottom of said oppositely disposed side wall panel sections.

2. A bag as set forth in claim 1, and said bottom reinforcing sealsextending inwardly at a 45 angle relative to the side edge seal anddefining triangular areas at the ends of said bottom wall which aredisposed in snug engagement with the overlying triangular wall portionsat the bottom of said side edge seals when the bottom portion of the bagis filled with a fiowable product.

3. A bag as set forth in claim 1 and said bottom reinforcing sealsextending at an angle of 45 relative to the gusset outer fold line anddefining triangular wall sections at opposite ends of the bottom wallwhich unfold into the plane of the side wall panel sections at thebottom of said side edge seals so as to be in substantial engagementwithin the corresponding triangular side wall sections when the bottomportion of the bag is filled with a fiowable product.

4. A bag formed of a sheet of heat sealable plastic film material whichsheet is folded upon itself with a bottom wall panel forming gusset atthe fold line and having side wall forming panels connected by side edgeseals in the form of hot knife welds, said side edge seals extendingfrom the outer gusset folds substantially the full dimension of thefolded sheet, and bottom reinforcing flat seals extending diagonallyinward from the junction of the gusset inner fold and the side edgeseals to the gusset outer folds, and joining the ends of the gussetfolds to the portions of the side walls which extend beyond saidjunction, with the confronting gusset fold portions free of each other,so that, when the bag bottom is opened up, triangular panel portionsextending on opposite sides of the edge seals at the bottom ofoppositely disposed side wall sections overlie triangular panel portionsat the opposite ends of the bottom wall panel, which triangular portionsopen into the plane of said oppositely disposed side wall panel sectionsand form therewith multi-ply reinforced triangular areas at the bottomof said side wall panel sections.

5. A bag as set forth in claim 4, and said bottom reinforcing sealsextending at a 45 angle to the gusset outer fold line and to the sideedge seals and defining triangular panel portions at opposite ends ofthe bottom wall panel which unfold into the plane of the oppositelydisposed side wall panel sections and lie in engagement with thecorresponding side wall panel sections when the bottom of the bag isopened up and filled with a fiowable product.

6. A method of fabricating bags from a web of heat sealable plastic filmmaterial which comprises folding the web upon itself about alongitudinal line with a gusset formed at the fold line and treating theseal forming areas of the innermost confronting faces of said gussetfolds to inhibit heat sealing between said innermost faces of saidfolds, applying flat heat seals at intervals along the gusset foldedmargin to form reinforcing seals in the confronting faces of the foldsand the adjoining side wall panels with the heat seals beibng V-shapedand opening outwardly of the folded Web and spaced a distancecorresponding to the width of collapsed bag desired, the apex of eachV-shaped seal being in a web severing and sealing line which extendstransversely of the path of advance of the web from the gusset outerfold lines substantially the full dimension of the folded sheet and eachV-shaped seal subtending an angle of 90 which is bisected by saidtransversely extending severing and sealing line, and severing andsealing said web on said transversely extending lines so as to formsuccessive side sealed bags with a rectangular bottom and withtriangular portions at the bottom of oppositely disposed side wall panelportions which triangular portions open up into the plane of theadjoining side wall sections and co-operate therewith in forming amulti-wall reinforced triangular area at the bottom of said side wallsections when the bottom is opened up.

References Cited UNITED STATES PATENTS 8/1968 Kugler 9333 X 4/1969Reiche 22960= X THERON E. CONDON, Primary Examiner N. ABRAMS, AssistantExaminer US. or. X.R.

